37mm Variable ND Filter Front Thread Size

Discussion in 'Accessories' started by eastmanw, Jul 21, 2015.

  1. eastmanw

    eastmanw New to Mu-43

    May 11, 2015
    Will Eastman
    I have a 37mm K&F Slim Variable ND Filter for my 14-42mm kit lens. The front of the lens has a thread on it that I would like to fit a second ND filter to. I am unsure of what size thread is on the front of the filter, measuring it show it to be just over 40mm but can't find anything online.

    Does anybody know what the thread is on the front of these nd filters?
  2. tkbslc

    tkbslc Mu-43 Legend

    I cannot imagine a filter that would have different thread sizes for the front and rear. 99.9% certain it would also be 37mm.
  3. dwig

    dwig Mu-43 Top Veteran

    Jun 26, 2010
    Key West FL
    If your "just over 40mm" measurement is the outside of the filter then the inside thread may well be 37mm.

    If you were measuring the inside then the thread size would be something over your measurement, perhaps between 40.5mm and 43mm, as thread sizes are spec'd using the outside diameter of the male thread.

    Either way, I would NOT recommend that you attached a second filter to the front of any variable filter (e.g. polarizer, variable ND, ...) since it is very very hard to hold the rotating ring when trying to remove the second finder from the front. I would suggest that if you need to add a second ND, that you add it behind the variable ND. Also, don't try to stack two variable filters.
  4. eastmanw

    eastmanw New to Mu-43

    May 11, 2015
    Will Eastman
    Ah thank you, I suspected that it would be measured this way, think it is probably a 41 although strangely 40.5 is a rather popular size.
    I would not be looking to add a variable ND but simply a standard ND. The reason for doing this after the variable is that 37mm ND's seem to be rather expensive.
    If you have any further advice regarding 37mm ND (in particular darker ones) that would be great.
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